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    ASTM D5523 - 21

    Standard Test Method for Polyurethane Raw Materials: Acidity by Argentometric Determination of Hydrolyzable Chlorine in Monomeric, Aromatic Isocyanates

    Active Standard ASTM D5523 | Developed by Subcommittee: D20.22

    Book of Standards Volume: 08.03

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    Significance and Use

    5.1 This test method is suitable for research or for quality control to characterize TDI and MDI.

    5.2 This test method was developed to overcome problems with low-level acidity determinations that use glass electrodes in the presence of reagent alcohol solvents. Reagent alcohols contain acidic and basic species, which complicate the glass electrode methods at low levels of acidity.

    1. Scope

    1.1 This test method measures the hydrolyzable chlorine content of monomeric, aromatic isocyanates used as polyurethane raw materials and expresses it as HCl acidity. The test method is applicable to toluene diisocyanate (TDI) and monomeric methylene di(phenylisocyanate), known as MDI. The main sources of hydrolyzable chlorine and, therefore, acidity in monomeric aromatic isocyanates are carbamyl chlorides, acid chlorides, and dissolved phosgene. All of these compounds react with alcohols and water to form hydrochloric acid.

    1.2 This test method applies only to monomeric isocyanates in which all of the acidity is derived from species that generate HCl on solvolysis.

    1.3 The values stated in SI units are to be regarded as the standard.

    1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.

    Note 1: There is no known ISO equivalent to this standard.

    1.5 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

    2. Referenced Documents (purchase separately) The documents listed below are referenced within the subject standard but are not provided as part of the standard.

    ASTM Standards

    D883 Terminology Relating to Plastics

    E456 Terminology Relating to Quality and Statistics

    E2935 Practice for Conducting Equivalence Tests for Comparing Testing Processes

    ICS Code

    ICS Number Code 83.080.20 (Thermoplastic materials)

    UNSPSC Code

    UNSPSC Code 12352100(Organic derivatives and substituted compounds)

    Referencing This Standard
    Link Here
    Link to Active (This link will always route to the current Active version of the standard.)

    DOI: 10.1520/D5523-21

    Citation Format

    ASTM D5523-21, Standard Test Method for Polyurethane Raw Materials: Acidity by Argentometric Determination of Hydrolyzable Chlorine in Monomeric, Aromatic Isocyanates, ASTM International, West Conshohocken, PA, 2021, www.astm.org

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